The data rate in PRML tests is very often limited by the PRML channel chip used for testing. Guzik has now developed a property PRML to test at data rate of 1Gb/s. This puts 1Gb/s test capability in your hand right away. No need to wait for PRML chips to become available. Soon Guzik channel will be the standard against which all channels will be compared.

In addition RWA-2585A PRML provides digital parametric measurements and digital scope functions. This increases the accuracy of all the measurements and reduces the test time.

A block diagram of the Guzik PRML channel is shown in Figure 1. Read back analog signal is digitized with high oversampling and stored in 4M bytes memory. This stored data is then processed to prepare test results. The speed of data processing in PRML mode is 40 M samples/s. PRML modes PR-4, EPR-4, E2PR4 can be chosen by software.

Figure 1. Guzik PRML Channel Block Diagram

Figure 2 shows the error rate measurements with the Guzik PRML channel for a data rate of 1Gbit/s.

Figure 2. Off-Track Perfomance at 1 Gbit/s

The same hardware is used for digital parametric measurements such as: TAA, PW, SNR, etc. The speed of the digital data processing in this mode is 80M samples /s. The digital measurements provide accurate results of TAA and PW measurements, even with a low signal-to-noise ratio. For example, for SNR as low as 12 dB, the accuracy of the measurements for repetitive patterns is better than 1.5%, when most other measuring equipment cannot provide stable measurements. (See Figure 3 and Figure 4.)

Figure 3. One Shot Mode, 12 dB SNR

Figure 4. The Same, After Averaging

Digital measurements implemented in the Guzik RWA-2585A PRML is the new paradigm. In future Guzik Technical Enterprises will provide most measurements based upon a digital approach. This will make it easy to change algorithms, introduce new tests that can not be done by analog circuitry, change the type of data decoding of the PRML channel, etc. For the same time RWA-2585A can provide analog parametric measurements.

Features:

Wide range of PRML tests, includes (but is not limited to):

Bit error rate measurements

Off-track channel performance

Histograms of sampled values distribution

Sequential amplitude margin (SAM) tests

Amplitude margin error rate prediction

Non-linear transition shift (NLTS) measurements:

Pseudo-random pattern auto-correlation

Harmonic elimination

Correlation noise

Optimization of PRML channels:

Based on error rate measurements

Based on channel quality monitor

Customized optimization algorithms

Signal Display:

2Gsamples/s 8 bits single shot mode, up to 4 Mbytes memory

Average mode

All industry-standard parametric measurements, based upon digital processing

Digital 20 taps Equalizer increases the accuracy of equalization and the flexibility of the PRML channel

Optional differentiators: two plug-in positions with data range from 5 to 250 MHzs

Optional differentiators: two plug-in positions with a data range from 5 to 250 Mflux/s

Built-in Spectrum Analyzer

Frequency range: from 0.5 to 400 MHz
Frequency resolution: 10 Hz

Accuracy: ±0.2 dB within 70 dB dynamic range

Selectivity: Switchable:

100 kHz at -3 dB; 500 kHz at -60 dB

140 kHz at -3 dB, 850 kHz at -60 dB

Video bandwidth: 100 kHz

Noise floor level: better than -80 dB

Write Channel

Frequency Synthesizer: up to 2 GHz with better than 1 Hz resolution

Frequency stability: ±2.5 ppm up to 75 C, ±1 ppm/year

Pattern generator: Up to 1G flux/s, programmable pattern up to a maximum of 32 Kbytes of encoded data and hierarchical pattern structure

Pre-compensation: three pre-compensation values with a 5 ps resolution can be assigned to any bit in a pattern, or an unlimited number of pre-compensation values at 20 ps resolution can be assigned to any bit in a pattern